Dumbbell Shaped Neurofibroma

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Dumbbell-Shaped Neurofibroma of the

Upper Cervical Spine: A Case ReportFeyzi Birol SARICA, Kadir TUFAN, Melih EKNMEZ, Blent ERDOAN,Orhan EN

Bakent University Medical Faculty, Department and Neurosurgery, Ankara

Spinal neurofibromas are the most prevalent group of spinal tumors. They occur sporadicallyor in association with Neurofibromatosis type-1 (NF1, von Recklinghausen disease). Aneurofibromas developing a dumbbell tumor is a situation which is quite often seen. Surgicalintervention is indicated when myelopathy and motor deficits develop in the case of paraspinal

neurofibromas. The goal of surgery is total removal of the tumor. However, in selected cases par-tial removal of the tumor with adequate spinal cord decompression can be preferred to preventsevere complications such as vertebral artery injury. We present a case of neurofibroma with neckand shoulder pain and dumbbell tumor formation at the level of C1 that was in close relation withthe vertebral artery. Possible surgical interventions are discussed.

Key words: Dumbbell formation, spinal neurofibroma, surgical treatment, upper servicalarea

J Nervous Sys Surgery 2008; 1(3):190-194

st Servikal Omurilik Blgesinde Gzlenen Kum Saati eklinde Nrofibroma: Olgu Sunumu

Spinal nrofibromlar spinal tmrlerin nemli bir ksmn oluturur. Sporadik yadaNrofibromatozis tip-1 (NF1, von Recklinghausen hastal) ile birlikte grlr. Nrofibromann

Dummbell tmr eklinde geliim gstermesi olduka sk grlen bir durumdur. Paraspinalnrofibroma olgularnda myelopati veya motor defisit gelitii durumlarda cerrahi endikasyondoar. Cerrahide ama tmrn total karmdr. Ancak seilmi vakalarda, vertabral arter yara-lanmas gibi ar komplikasyonlardan kanmak amacyla, yeterli spinal kord dekompresyonusalayacak ekilde parsiyel karm seilebilir. Bu makalede, C1 dzeyinde vertabral arter ileyakn ilikide olan, boyun ve omuz ars ile prezente olan dummbbell nrofibroma olgusu sunul-mutur. Secilebilecek cerrahi giriim ekilleri tartlmtr.

Anahtar kelimeler: Cerrahi tedavi, kum saati formasyonu, spinal nrofibroma, st servikalblge

J Nervous Sys Surgery 2008; 1(3):190-194

Nodular neurofibromas may occur any-where on the peripheral nerves. They

frequently originate from the dorsal

roots and invade the sensorial branches. They

are capsulated and have a round and flexible

structure (3,5,7,8). No treatment is needed for

asymptomatic neurofibroma cases. Symptomatic

cases justify surgical treatment. Surgical treat-

ment of neurofibromas is total removal. Posterior

laminectomy with unilateral facetectomy allows

single-stage resection of dumbbell neurofibro-mas with significant intraspinal and paraspinal

components. Best results are obtained from pati-

ents with minimal neurological deficits in the

preoperative period (4,8,11,14).

CASE REPORT

A 61-year-female was admitted to the hospital

with pain over the neck, left shoulder and arm.

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Sinir Sistemi Cerrahisi Derg 1(3):190-194, 2008


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Neurological examination revealed left-sided

spastic hemiparesis, more pronounced distally

hypoesthesia below C2 dermatome and hyperac-

tive deep tendon reflexes. T1-weighted magnetic

resonance imaging (MRI) of the cervical spineshowed a hypointense mass measuring 1.5x2x2.5

cm and occupying the left neural foramen and

left half of the spinal canal. The lesion had a

prominent hyperintense center with a hypointen-

se periphery on T2-weighted images. There was

a marked contrast enhancement of the periphery

of the lesion following gadolinium injection.

Intradural component of the mass was found to

compress the left side of the spinal cord while

the extradural component was close to the ver-

tebral artery (Figures 1A and 1B). Vertebral

angiography was performed to determine the

course of the vertebral artery (VA) and to plan

the surgical procedure. Cranial diffusion-

perfusion MRI performed to depict cerebral

vascularization and collateral circulation was

normal.

The patient was operated via a posterior exposu-

re with posterior arc of C1 and C2 removed.

During the partial resection, foraminal and ext-

radural components were left in situ while the

intradural component of the tumor which comp-

ressed the spinal cord at the levels of C1 and C2

and contained nerve rootlets was totally excised

to achieve spinal cord decompression. Since the

case was considered as a neurofibroma, there

were possibilities of spinal cord compression by

the intradural component and adhesions of the

extradural component to the vertebral artery and

venous structures around it. Therefore, care was

taken not to cause traction during the dissection.Histopathological diagnosis of the resected spe-

cimen was neurofibroma.

Postoperative neurological examination revea-

led left hemiparesis (4/5 motor strength).

Physical therapy and rehabilitation was given.

At 4 months followed-up, neurological exami-

nation was normal and neck pain was comple-

tely resolved. Removal of intradural component

of the neurofibroma and adequate decompressi-

on of the spinal cord was seen on postoperative

cervical spine MRI (Figures 2A and 2B).

Figure 1. (A) A hyperintense mass overlying the left transverseprocess was observed on preoperative, sagittal, contrast-enhanced, T1-weighted magnetic resonance images of thespine. (B) On axial, contrast-enhanced T1-weighted magneticresonance images of the patient performed preoperatively, ahyperintense mass, with intra and-extradural components,extending toward the left transverse process was observed.

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Dumbbell-Shaped Neurofibroma of the Upper Cervical Spine: A Case Report


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DISCUSSION

Of the paraspinal neurofibromas; 72 % were

with intradural extramedullar localization, where

as 14 % were with extradural, 13 % were withdumbbell formation and 1 % was with intrame-

dullary localizations (5,7,16). A neurofibroma in the

spinal canal, invading the peripheral segment of

the nerve by extending out of the intervertebral

foramen and presenting itself with a dumbbell

tumor is quite common. In the series of cases

presented by Seppala et al., 21 (66 %) of 32

neurofibromas demonstrated both intradural and

extradural tumor components, and 17 tumors

extended laterally through the foramina. In these

dumbbell neurofibromas, the extraspinal part is

usually larger than the intraspinal part (14). Tumor

with may reach massive dimensions, be lobula-

ted and exhibit cystic degeneration. Dumbbellformation is important due to the attachment of,

especially, the extramedullary part to the surro-

unding tissues. Its vicinity to the VA is critical(10,13,14).

Clinical findings develop as a result of local

compression of the ventral or motor nerve roots.

While root symptoms develop during the early

period, long-tract findings develop later. Cervical

and lumbar regions are more frequently invaded.

Radicular pain and disesthesia were present in

80 % cases. Motor weakness that we detected in

our case is seen in some 10 % of the cases(5,8,11).

Direct radiographs are sufficient to establish

diagnosis in 50 % of the cases. Pedicle erosion

and vertebral body scalloping are the most fre-

quent findings on direct radiograph. Regular

expansion of the interpedicular distance and

intervertebral foramen may directly indicate the

presence of the dumbbell tumor. Thanks to its

sensitivity and specificity, MRI is quite impor-

tant in detecting the disease, determining the

accompanying pathologies and following the

development of the complications in NF1 cases.

Neurofibromas appear as iso- or hyperintense to

the spinal cord on T1-weighted images while

they give hyperintense signal on T2-weighted

images. Dumbbell neurofibromas enhance regu-

larly upon gadolinium administration (5,6,15).

No treatment is needed for asymptomatic neuro-

fibroma cases. Symptomatic cases justify surgi-

cal treatment. Majority of the nerve fibers are

entrapped within tumoral tissue in dumbbell

neurofibroma cases, as in our case. It is impos-

sible to remove the tumor without sacrificing the

nerve root and aggressive surgery may result in

severe neurological deficits (8,10). Thus, partial

Figure 2. Sagittal (A) and axial (B) T2-weighted MR images ofthe cervical spine of the patient taken 2 months after the ope-ration clearly show that the intradural component of thetumor at the level of C1-C2 was excised and there was nospinal cord compression.


F. B. Sarca, K. Tufan, M. ekinmez, B. Erdoan, O. en


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resection should be preferred in dumbbell neuro-

fibroma cases that cause compression of the

spinal cord. As the aim of partial resection is to

resolve the symptoms, the extent of surgical

treatment is shaped according to the clinicalpicture of the patient. Our patient presented with

myelopathic findings and, therefore, decompres-

sive excision of the tumor was planned. In

decompression surgery, intradural component of

the tumor that compressed the spinal cord was

excised but foraminal and extradural compo-

nents were left. Decompressive surgery is a

partial resection that carries with itself the risk

of recurrence and surgery may be needed(5,8,9,10,11).

Dumbbell tumors with significant dissemination

into the paraspinal region may require complex

spinal exposure. Although two-stage operations

may be performed to manage the intraspinal and

paraspinal components separately, a single-stage

procedure is preferable. For cervical tumors, the

VA is another issue to be considered. In most

instances, meningiomas and nerve sheath tumors

receive little blood from the spinal cord and are

attached by few adhesions to the spinal cord.

Most cervical dumbbell tumors can be adequa-

tely accessed through a standard laminectomy

and complete unilateral facetectomy. As in our

case, this allows paraspinal access up to 3 cm

from the lateral dural margin. A second-stage

anterior procedure may be required if further

tumor extension is present (2,4,10,12).

The VA is consistently displaced anteromedially

by dumbbell neurofibromas of the cervical

spine. The artery is neither encased nor invadedby these tumors but is separated from the tumor

capsule by a thin layer of periosteum and peri-

vertebral veins. These tissues serve as an effec-

tive and easily developed plane of dissection

that is rarely associated with VA injury. Thus,

because of the low risk of either VA injury or its

potential ischemic consequences, preoperative

angiography and/or test occlusion or early intra-

operative control and mobilization do not seem

warranted (4,10,13).

The incidence of cervical spine instability after

unilateral facetectomy and varying degrees oflaminectomy is unknown. In an experimental

study by Cusick et al., isolated unilateral cervi-

cal facetectomy resulted in an average loss of

strength of 31.6 % in response to a constant fle-

xion/compression load, as compared with an

intact motion segment (1). Although acute spinal

instability did not occur in the clinical study by

McCormick et al., the significant loss of mecha-

nical integrity associated with unilateral facetec-

tomy presented a continued risk of delayed ins-

tability from repetitive loading (11). This risk

probably increases in proportion to the amount

of concomitant laminar ant ligamentous disrup-

tion. Independent factors, such as patient age,

spinal mobility, individualized loading patterns,

and spinal level, might also be relevant.

Contralateral facet fusion prevents delayed ins-

tability.

Prognosis is excellent after the surgical resecti-

on. While pain is diminished in 80 % of the

cases, total remission occurs in 60 % of the

cases. Recurrence is very rare subsequent to

total excision. Recurrence after 3 years was

noted in one of 66 paraspinal neurofibroma pati-

ents who were treated by Levy et al. (8). However,

upper cervical neurofibroma cases characterized

by dumbbell formation, as in our case, are trea-

ted by partial resection, thus they have the risk

of recurrence. It is crucial to screen cervical

spine in these patients by advanced imaging

modalities such as MRI to detect recurrence(5,10,11,14).

CONCLUSION

The most significant feature of dumbbell neuro-

fibromas is the adhesion of the tumor to the

environment by enlarging the foramen and pro-

jecting outward from the spinal canal (8,10,11). The

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Dumbbell-Shaped Neurofibroma of the Upper Cervical Spine: A Case Report


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goal of surgery is total removal of the tumor.

Although a variety of surgical approaches for

these lesions is available, most cervical spine

dumbbell tumors can be effectively managed

with a single-stage posterior exposure with par-tial laminectomy and unilateral facetectomy(4,8,10,13,14). However, in selected cases partial

removal of the tumor with adequate spinal cord

decompression can be preferred to prevent ver-

tebral artery injury.

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F. B. Sarca, K. Tufan, M. ekinmez, B. Erdoan, O. en

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